The present invention relates to a system for tensioning a belt. More particularly, certain embodiments of the present invention relate to a pivot plate that engages a belt on a mobile C-arm to increase the tension of the belt.
Before and during a medical procedure, medical professionals may need to take several different images of a patient's body from a number of different orientations. Often it is difficult to effectively capture images from certain orientations where the imaging device is fixed and stationary. Therefore, imaging devices are mounted on large, mobile structures known as C-arm imaging machines. C-arm imaging machines typically include a mobile support structure, a carrier, and a curved, C-shaped positioning arm, (or C-arm). The carrier is mounted on the support structure and the C-arm is, in turn, slidably mounted to the carrier. An imaging source is located on one distal end of the C-arm and an imaging receiver is located on the other distal end of the C-arm. The C-arm imaging machine may be moved and rotated about a patient in a number of different orientations such that the patient is positioned between the imaging source and the imaging receiver. The C-arm imaging machine operator may then take an image of the patient.
The C-arm typically may be rotated about the patient in at least two ways. The support structure includes a rotation arm that is connected to the carrier. The C-arm has tracks along an outer periphery thereof that capture rollers on the carrier such that the C-arm is movably retained to the carrier along the rollers. A large belt extends from the carrier around the arms of the C-arm. The rotation arm may be rotated about a rotational axis such that the C-arm also rotates about the rotational axis. This is known as the rotational rotation of the C-arm. Additionally, the C-arm may be rotated along the plane of the C-arm about a transverse axis by moving the belt such that the C-arm moves, or rotates, along the carrier. This is known as orbital rotation of the C-arm. By being rotatable about at least two different axes, the C-arm may be positioned at many different orientations about a patient in order to take images from different desirable perspectives. Thus, the mobile C-arm imaging machine greatly increases the efficiency and ease of taking images of a patient before and during a medical procedure.
However, the conventional mobile C-arm imaging machine has a number of drawbacks. First, many C-arms may only be moved manually for either orbital or rotational rotation. That is to say, an operator must manually release a brake and then manipulate the C-arm to move the C-arm to a desired position. The operator then manually stops the movement of the C-arm when it reaches its desired position and activates the brake to lock the C-arm in place. This method of adjusting the position of the C-arm can be difficult and time-consuming, especially if the person performing the medical procedure must also manipulate the C-arm. Additionally, this method of adjusting the position of the C-arm may lead to imprecise positioning by the operator or any other number of problems caused by human error.
Some conventional C-arms have a drive train that is connected to the C-arm such that an operator can use the drive train to mechanically drive the C-arm to orbitally rotate about the carrier. The operator can thus control the movement of the C-arm by operating a joystick that is electrically connected to the drive train. However, often the C-arm imaging machines that incorporate such drive trains are large fixed-room devices that cannot be moved out of a room for use. Additionally, the drive train is in a fixed position such that is cannot be moved with the C-arm and thus may take up space and get in the way of operation of the C-arm. Additionally, there are other conventional C-arms that are mobile and incorporate a drive train, but these C-arms do not use a belt to drive the C-arm.
Another problem associated with conventional C-arm imaging machines is maintaining tension in the belt as it engages the C-arm, and, if applicable, the drive train. The belt needs to be tensioned about the C-arm and the carrier in order that an operator can effectively move the belt and thus cause the C-arm to rotate orbitally. If the belt is not adequately tensioned, the belt may be delayed in engaging the distal ends of the C-arm. Also, in C-arms that include drive trains, if the belt is not adequately tensioned, the drive train may not fully engage the belt or the belt may lay even loosely about the rotating pulleys of the drive train.
Thus, many conventional C-arms include a tensioning system, or spring, located at a first distal end of the C-arm that resistibly engages the belt and pushes the belt away from the C-arm in order to tension the belt about the C-arm. The C-arms do not necessarily include a spring at the opposite second distal end of the C-arm. Because the spring is located at only the first end of the C-arm, the tension in the belt decreases at points further away from the first end. If the C-arm includes a drive train, the drive train engages the belt between the two distal ends of the C-arm. Therefore, the tension of the belt is different on either side of where the belt is connected to the drive train. For example, the section of the belt extending from the drive train to the second distal end is not as tensioned as the section of the belt extending from the drive train to the first distal end. Because of the increased slack in the belt between the second distal end and the drive train, rotation of the C-arm may be delayed where the operator tries to rotate the second distal end toward the drive train.
Additionally, locating the tensioning system at either end or both ends of the C-arm takes up space such that the tensioning system may limit the mobility of the C-arm or get in the way of the operator or medical procedure taking place.
Therefore, a need exists for an improved tensioning and drive system for a belt used to move a C-arm.